The long-term objective of the proposed research is to develop improved techniques for the production of identical animals by nuclear transplantation which can be sold and/or used for scientific research. The ability to produce genetically identical animals would no doubt result in a tremendous cost reduction for experimentation involving both human and animal health. Valuable transgenic animals might be created and mass produced by nuclear transplantation far more efficiently than is possible when using identical animals. More important, especially today with society becoming more concerned with animal welfare; far fewer animals are required for experimentation to become statistically valid. The specific aim of this work is to test the hypothesis that the amount of cytoplasm available for early embryonic development has a significant effect on the development of embryos produced by nuclear transplantation. This will be accomplished by using micromanipulation to alter the amount of cytoplasm available for early embryonic development of bovine embryos produced by in vitro maturation, in vitro fertilization, and nuclear transplantation. The embryos will then be cultured in vitro, and embryonic development monitored and compared between different types of embryos.